TRAPPIST-1b

Last updated

TRAPPIST-1b
TRAPPIST-1 b comparison.png
Earth and TRAPPIST-1b compared
Discovery [1]
Discovered by Michaël Gillon et al.
Discovery site TRAPPIST
Discovery dateMay 2, 2016
Transit
Orbital characteristics [2]
0.01154 ± 0.00010 AU (1,726,000 ± 15,000 km)
Eccentricity 0.00622±0.00304 [3]
1.510826 ± 0.000006 d (36.25982 ± 0.00014 h)
Inclination 89.728°±0.165°
336.86°±34.24° [3]
Star TRAPPIST-1 [4]
Physical characteristics [2]
1.116+0.014
−0.012  R🜨
Mass 1.374±0.069  M🜨
Mean density
5.425+0.265
−0.272  g/cm3
1.102±0.052 g
10.80±0.51  m/s2
Temperature 397.6±3.8  K (124.5 °C; 256.0 °F, equilibrium) [5]
503+26
−27  K (230 °C; 446 °F, surface) [6]
Atmosphere
Composition by volume None or extremely thin [6] [7]

    TRAPPIST-1b is a mainly rocky exoplanet orbiting around the ultra-cool dwarf star TRAPPIST-1, located 40.7 light-years (12.5 parsecs ) away from Earth in the constellation of Aquarius. The planet was detected using the transit method, where a planet dims the host star's light as it passes in front of it. It was first announced on May 2, 2016, [1] and later studies were able to refine its physical parameters.

    Contents

    The planet is about 37% more massive than Earth and about 39% larger in volume; thus its density is very similar. It is the innermost of seven planets orbiting TRAPPIST-1, all of which are terrestrial, but is too close to its star to be in the habitable zone. Observations by the James Webb Space Telescope announced in 2023 suggest that it does not have any significant atmosphere. [6] [7] Its albedo is very low, making it dark in color.

    Physical characteristics

    Mass, radius, and temperature

    TRAPPIST-1b is very similar in both mass, radius, and gravity to Earth. It has a radius of 1.116  R🜨 , a mass of 1.374  M🜨 , and about 110% Earth's surface gravity. [2] Initial estimates of the planet's density suggested that it is not entirely rocky; with a density of 3.98 g/cm3, about ≤5% of its mass must be volatiles, likely in the form of a thick Venus-like atmosphere due to it receiving nearly four times more energy than Earth does. [3] However, refined density estimates show that the planet is only slightly less dense than Earth. [2]

    Assuming the presence of an atmosphere, the planet's surface temperature was initially estimated to be between 750 K (477 °C; 890 °F) and 1,500 K (1,230 °C; 2,240 °F), potentially as high as 2,000 K (1,730 °C; 3,140 °F). This is much hotter than the surface of Venus and may be hot enough that the surface is molten lava. [3] An observation of the secondary eclipse of TRAPPIST-1b by the James Webb Space Telescope, announced in 2023, suggests that the planet does not have any significant atmosphere, with a measured surface temperature of about 503 K (230 °C; 446 °F), [6] [7] and a low albedo. [8] The planet may be very geologically active due to tidal squeezing similar to Jupiter's moon Io, which happens to have a similar orbital period and eccentricity (see TRAPPIST-1#Resonance and tides for references).

    Orbit

    TRAPPIST-1b orbits very close to its parent star. One orbit requires only 36 hours, or about 1.51 Earth days. [9] It orbits about 0.0115  AU (1.72 million  km ; 1.07 million  mi ) from its star, just 1.2% the distance between Earth and the Sun. [3] The close proximity to its host star means that TRAPPIST-1b is likely tidally locked. It also has a very circular orbit, with an eccentricity of 0.00622, significantly more circular than Earth's orbit, which has an eccentricity of 0.0167086.

    Host star

    TRAPPIST-1b orbits the ultracool red dwarf star TRAPPIST-1. It has a mass of 0.089 M☉ and is only 0.121 R☉, with a surface temperature of 2,511 K (2,238 °C; 4,060 °F) and an age between 3 and 8 billion years. The Sun, in comparison, has a surface temperature of 5,778 K (5,505 °C; 9,941 °F) and is about 4.5 billion years old. TRAPPIST-1 is also very dim, with a luminosity about 0.0005 times that of the Sun. It is too faint to be seen with the naked eye, having an apparent magnitude of 18.80.

    Atmosphere

    Artist's impression of TRAPPIST-1b (March 2023) Rocky exoplanet TRAPPIST-1 b (illustration) (weic2309a).jpg
    Artist's impression of TRAPPIST-1b (March 2023)

    The combined transmission spectra of TRAPPIST-1 b and c rule out cloud-free hydrogen-dominated atmospheres for both planets, so they are unlikely to harbor extended gas envelopes. Also, no helium emission from TRAPPIST-1b has been detected. [10] Prior to JWST observations, other atmospheres, from a cloud-free water-vapor atmosphere to a Venus-like atmosphere, remained consistent with the featureless spectra. [11]

    In 2018, the planet's atmosphere was better examined by the Spitzer Space Telescope and suggested to be quite large and hot, although the presence of an atmosphere could not be confirmed. The planet's transmission spectrum and refined density estimate suggested two main possibilities for the atmosphere: one rich in carbon dioxide, or one rich in water vapor. The more likely CO2 atmosphere would have a scale height of approximately 52 kilometers (32 miles) (Earth's being 8 km (5.0 mi), and Venus' at 15.9 km (9.9 mi)) and an average temperature in excess of 1,400 K (1,130 °C; 2,060 °F), far greater than the planet's equilibrium temperature of 397.6 K (124.5 °C; 256.0 °F). A water vapor atmosphere would need to have a scale height of >100 km (62 mi) and a temperature >1,800 K (1,530 °C; 2,780 °F) to produce the variations seen in the planet's transit depths and its transmission spectrum, and would be vulnerable to photodissociation where CO2 would not be. Other sources for the effects seen, such as hazes and thick clouds, would require an even larger atmosphere. TRAPPIST-1b will have to be studied further to confirm its potential large atmosphere. [9] [3]

    An observation of the secondary eclipse of TRAPPIST-1b by the James Webb Space Telescope, announced in March 2023, suggests that the planet does not have any significant atmosphere. [6] [7] Atmospheres containing carbon dioxide with surface pressures greater than 0.1  bar can be ruled out at 3-sigma, and pressures greater than 0.01 bar at 1-sigma. [8] Further studies of the exoplanet by transmission spectroscopy (primary eclipse), reported in September 2023, also confirmed the absence of a hydrogen-rich atmosphere, but due to stellar contamination were unable to determine the presence or absence of other types of atmospheres based on the transmission spectroscopy data alone. This does not affect the previous results based on emission spectroscopy. [12] [13]

    See also

    Related Research Articles

    <span class="mw-page-title-main">Wide Angle Search for Planets</span> Exoplanet search project

    WASP or Wide Angle Search for Planets is an international consortium of several academic organisations performing an ultra-wide angle search for exoplanets using transit photometry. The array of robotic telescopes aims to survey the entire sky, simultaneously monitoring many thousands of stars at an apparent visual magnitude from about 7 to 13.

    <span class="mw-page-title-main">Transit-timing variation</span> Exoplanet detection method using transit timing variations

    Transit-timing variation is a method for detecting exoplanets by observing variations in the timing of a transit. This provides an extremely sensitive method capable of detecting additional planets in the system with masses potentially as small as that of Earth. In tightly packed planetary systems, the gravitational pull of the planets among themselves causes one planet to accelerate and another planet to decelerate along its orbit. The acceleration causes the orbital period of each planet to change. Detecting this effect by measuring the change is known as transit-timing variations. "Timing variation" asks whether the transit occurs with strict periodicity or if there's a variation.

    <span class="mw-page-title-main">TRAPPIST-1</span> Ultra-cool red dwarf star in the constellation Aquarius

    TRAPPIST-1 is a cool red dwarf star with seven known exoplanets. It lies in the constellation Aquarius about 40.66 light-years away from Earth, and has a surface temperature of about 2,566 K. Its radius is slightly larger than Jupiter and it has a mass of about 9% of the Sun. It is estimated to be 7.6 billion years old, making it older than the Solar System. The discovery of the star was first published in 2000.

    <span class="mw-page-title-main">SPECULOOS</span> Astronomical observatory

    SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) is a project consisting of SPECULOOS Southern Observatory (SSO) at the Paranal Observatory in Chile and SPECULOOS Northern Observatory (SNO) at the Teide Observatory in Tenerife.

    <span class="mw-page-title-main">TRAPPIST-1d</span> Small Venus-like exoplanet orbiting TRAPPIST-1

    TRAPPIST-1d, is a small exoplanet, which orbits on the inner edge of the habitable zone of the ultracool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation of Aquarius. The exoplanet was found by using the transit method. The first signs of the planet were announced in 2016, but it was not until the following years that more information concerning the probable nature of the planet was obtained. TRAPPIST-1d is the second-least massive planet of the system and is likely to have a compact hydrogen-poor atmosphere similar to Venus, Earth, or Mars. It receives just 4.3% more sunlight than Earth, placing it on the inner edge of the habitable zone. It has about <5% of its mass as a volatile layer, which could consist of atmosphere, oceans, and/or ice layers. A 2018 study by the University of Washington concluded that TRAPPIST-1d might be a Venus-like exoplanet with an uninhabitable atmosphere. The planet is an eyeball planet candidate.

    <span class="mw-page-title-main">TRAPPIST-1c</span> Rocky exoplanet orbiting TRAPPIST-1

    TRAPPIST-1c, also designated as 2MASS J23062928-0502285 c, is a mainly rocky exoplanet orbiting around the ultracool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation Aquarius. It is the third most massive and third largest planet of the system, with about 131% the mass and 110% the radius of Earth. Its density indicates a primarily rocky composition, and observations by the James Webb Space Telescope announced in 2023 suggests against a thick CO2 atmosphere, however this does not exclude a thick abiotic oxygen-dominated atmosphere as is hypothesized to be common around red dwarf stars.

    <span class="mw-page-title-main">TRAPPIST-1f</span> Earth-size exoplanet orbiting TRAPPIST-1

    TRAPPIST-1f, also designated as 2MASS J23062928-0502285 f, is an exoplanet, likely rocky, orbiting within the habitable zone around the ultracool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation of Aquarius. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured.

    <span class="mw-page-title-main">TRAPPIST-1g</span> Earth-size exoplanet orbiting TRAPPIST-1

    TRAPPIST-1g, also designated as 2MASS J23062928-0502285 g and K2-112 g, is an exoplanet orbiting around the ultra-cool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation Aquarius. It was one of four new exoplanets to be discovered orbiting the star in 2017 using observations from the Spitzer Space Telescope. The exoplanet is within the optimistic habitable zone of its host star. It was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured.

    <span class="mw-page-title-main">TRAPPIST-1e</span> Earth-size exoplanet orbiting TRAPPIST-1

    TRAPPIST-1e, also designated as 2MASS J23062928-0502285 e, is a rocky, close-to-Earth-sized exoplanet orbiting within the habitable zone around the ultracool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation of Aquarius. Astronomers used the transit method to find the exoplanet, a method that measures the dimming of a star when a planet crosses in front of it.

    <span class="mw-page-title-main">TRAPPIST-1h</span> Cold Earth-size exoplanet orbiting TRAPPIST-1

    TRAPPIST-1h, also designated as 2MASS J23062928-0502285 h, is an exoplanet orbiting around the ultra-cool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation Aquarius. It was one of four new exoplanets to be discovered orbiting the star in 2017 using observations from the Spitzer Space Telescope. In the following years, more studies were able to refine its physical parameters.

    <span class="mw-page-title-main">LHS 1140 b</span> Super-Earth orbiting LHS 1140

    LHS 1140 b is an exoplanet orbiting within the conservative habitable zone of the red dwarf LHS 1140. Discovered in 2017 by the MEarth Project, LHS 1140 b is about 5.6 times the mass of Earth and about 70% larger in radius, putting it within the super-Earth category of planets. It was initially thought to be a dense rocky planet, but refined measurements of its mass and radius have found a lower density, indicating that it is likely an ocean world with 9-19% of its mass composed of water. LHS 1140 b orbits entirely within the star's habitable zone and gets 43% the incident flux of Earth. The planet is 49 light-years away and transits its star, making it an excellent candidate for atmospheric studies with ground-based and/or space telescopes.

    K2-315b is an exoplanet located 185.3 light years away from Earth in the southern zodiac constellation Libra. It orbits the red dwarf K2-315.

    WASP-72 is the primary of a binary star system. It is an F7 class dwarf star, with an internal structure just on the verge of the Kraft break. It is orbited by a planet WASP-72b. The age of WASP-72 is younger than the Sun at 3.55±0.82 billion years.

    WASP-62, formally named Naledi, is a single star about 573 light-years away. It is an F class main-sequence star, orbited by a planet, WASP-62b. The age of WASP-62 is much younger than the Sun at 0.8±0.6 billion years, and it has a metal abundance similar to the Sun.

    WASP-88 is a F-type main-sequence star. Its surface temperature is 6450±61 K. WASP-88 is similar to the Sun in its concentration of heavy elements, with a metallicity Fe/H index of 0.03±0.04, and is younger at an age of 3.0±1.3 billion years.

    WASP-80 is a K-type main-sequence star about 162 light-years away from Earth. The star's age is much younger than the Sun's at 1.352±0.222 billion years. WASP-80 could be similar to the Sun in concentration of heavy elements, although this measurement is highly uncertain.

    <span class="mw-page-title-main">WASP-96b</span> Gas giant exoplanet targeted for spectroscopy

    WASP-96b is a gas giant exoplanet. Its mass is 0.48 times that of Jupiter. It is 0.0453 AU from the class G star WASP-96, which it orbits every 3.4 days. It is about 1,140 light-years away from Earth, in the constellation Phoenix. It was discovered in 2013 by the Wide Angle Search for Planets (WASP).

    References

    1. 1 2 Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M.; Delrez, Laetitia; et al. (May 2016). "Temperate Earth-sized planets transiting a nearby ultracool dwarf star". Nature. 533 (7602): 221–224. arXiv: 1605.07211 . Bibcode:2016Natur.533..221G. doi:10.1038/nature17448. ISSN   1476-4687. PMC   5321506 . PMID   27135924.
    2. 1 2 3 4 Agol, Eric; Dorn, Caroline; Grimm, Simon L.; Turbet, Martin; et al. (1 February 2021). "Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides". The Planetary Science Journal. 2 (1): 1. arXiv: 2010.01074 . Bibcode:2021PSJ.....2....1A. doi: 10.3847/psj/abd022 . S2CID   222125312.
    3. 1 2 3 4 5 6 Grimm, Simon L.; Demory, Brice-Olivier; Gillon, Michael; Dorn, Caroline; Agol, Eric; Burdanov, Artem; Delrez, Laetitia; Sestovic, Marko; Triaud, Amaury H.M.J.; Turbet, Martin; Bolmont, Emeline; Caldas, Anthony; de Wit, Julien; Jehin, Emmanuel; Leconte, Jeremy; Raymond, Sean N.; Van Grootel, Valerie; Burgasser, Adam J.; Carey, Sean; Fabrycky, Daniel; Heng, Kevin; Hernandez, David M.; Ingalls, James G.; Lederer, Susan; Selsis, Franck; Queloz, Didier (2018). "The nature of the TRAPPIST-1 exoplanets". Astronomy & Astrophysics. 613: A68. arXiv: 1802.01377 . Bibcode:2018A&A...613A..68G. doi:10.1051/0004-6361/201732233. S2CID   3441829.
    4. ↑ Van Grootel, Valerie; Fernandes, Catarina S.; Gillon, Michaël; Jehin, Emmanuel; Scuflaire, Richard; et al. (2018). "Stellar parameters for TRAPPIST-1". The Astrophysical Journal. 853 (1): 30. arXiv: 1712.01911 . Bibcode:2018ApJ...853...30V. doi: 10.3847/1538-4357/aaa023 . S2CID   54034373.
    5. ↑ Ducrot, E.; Gillon, M.; Delrez, L.; Agol, E.; et al. (1 August 2020). "TRAPPIST-1: Global results of the Spitzer Exploration Science Program Red Worlds". Astronomy & Astrophysics. 640: A112. arXiv: 2006.13826 . Bibcode:2020A&A...640A.112D. doi:10.1051/0004-6361/201937392. ISSN   0004-6361. S2CID   220041987.
    6. 1 2 3 4 5 Greene, Thomas P.; Bell, Taylor J.; Ducrot, Elsa; Dyrek, Achrène; Lagage, Pierre-Olivier; Fortney, Jonathan J. (March 2023). "Thermal Emission from the Earth-sized Exoplanet TRAPPIST-1 b using JWST". Nature . 618 (7963): 39–42. arXiv: 2303.14849 . Bibcode:2023Natur.618...39G. doi:10.1038/s41586-023-05951-7. PMID   36972683. S2CID   257767242.
    7. 1 2 3 4 "NASA's Webb Measures the Temperature of a Rocky Exoplanet". webbtelescope.org. STScI. 27 March 2023. Retrieved 27 March 2023.
    8. 1 2 Ih, Jegug; Kempton, Eliza M.-R.; Whittaker, Emily A.; Lessard, Madeline (May 2023). "Constraining the Thickness of the Atmosphere of TRAPPIST-1 b from its JWST Secondary Eclipse Observation". The Astrophysical Journal Letters . 952 (1): L4. arXiv: 2305.10414 . Bibcode:2023ApJ...952L...4I. doi: 10.3847/2041-8213/ace03b .
    9. 1 2 Delrez, Laetitia; Gillon, Michael; H.M.J, Amaury; Brice-Oliver Demory, Triaud; de Wit, Julien; Ingalls, James; Agol, Eric; Bolmont, Emeline; Burdanov, Artem; Burgasser, Adam J.; Carey, Sean J.; Jehin, Emmanuel; Leconte, Jeremy; Lederer, Susan; Queloz, Didier; Selsis, Franck; Grootel, Valerie Van (2018). "Early 2017 observations of TRAPPIST-1 with Spitzer". Monthly Notices of the Royal Astronomical Society. 475 (3): 3577–3597. arXiv: 1801.02554 . Bibcode:2018MNRAS.475.3577D. doi: 10.1093/mnras/sty051 .
    10. ↑ Krishnamurthy, Vigneshwaran; et al. (2021), "Nondetection of Helium in the Upper Atmospheres of TRAPPIST-1b, e, and F", The Astronomical Journal, 162 (3): 82, arXiv: 2106.11444 , Bibcode:2021AJ....162...82K, doi: 10.3847/1538-3881/ac0d57
    11. ↑ de Wit, Julien; et al. (2016). "A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c". Nature. 537 (7618): 69–72. arXiv: 1606.01103 . Bibcode:2016Natur.537...69D. doi:10.1038/nature18641. PMID   27437572. S2CID   205249853.
    12. ↑ Sherburne, Morgan (25 September 2023). "James Webb Space Telescope's first spectrum of a TRAPPIST-1 planet". Phys.org . Archived from the original on 29 September 2023. Retrieved 29 September 2023.
    13. ↑ Lim, Olivia; et al. (22 September 2023). "Atmospheric Reconnaissance of TRAPPIST-1 b with JWST/NIRISS: Evidence for Strong Stellar Contamination in the Transmission Spectra". The Astrophysical Journal Letters . 95 (1): L22. arXiv: 2309.07047 . Bibcode:2023ApJ...955L..22L. doi: 10.3847/2041-8213/acf7c4 .
    14. ↑ "Artist's view of planets transiting red dwarf star in TRAPPIST-1 system". www.spacetelescope.org. Retrieved 21 July 2016.
    This page is based on this Wikipedia article
    Text is available under the CC BY-SA 4.0 license; additional terms may apply.
    Images, videos and audio are available under their respective licenses.